It would be nice if the Web Gallery in Lightroom and Bridge would allow an easy way to add a home page link to allow users & clients not only to see the Gallery but get an entry point into your main web site. I know this has been asked - but there is a way. Manual and a tad time consuming, but adding a small amount of XML/HTML it can be done.
When you create a Flash Web Gallery it created a number of XML files in the Resource Directory. Navigate to this directory and open the file called group.xml
Here is where you need at add a snippet of code and here is the example - not elegant but I am not a programmer 
Look for a section called custom it will look like <custom> and under the <siteTitle> add the code highlighted in red. The http reference should be red but the formatting of this page will not allow
<custom>
<siteTitle>Sunol Wilderness</siteTitle>
<groupTitle>
<a href="To Main Page</a>
</groupTitle>
<groupTitle> Here is the Group Title You Created....
Edit Arrgh the formatting of this page stripped out the link after the first " ---- so you will need to add your full URL including http and www of your home page.... just like below....
Now save the file and then upload the package as you normally would and at the top of the page of your Flash Gallery will be the link you inserted.
As I said not very elegant but it does work....
Hope this helps someone out and all the best for a magic 2013 - and you never know once Adobe sees how easy this is to do they will add an input box to the Web Gallery Creator 
Mike